There will be equipment compatibility issues to investigate, component and board procurement, and compatibility problems to address. There will be lead-free process validation studies, lead-free product implementation plans to execute and training for line supervisors and operators to be done. All this takes a company’s commitment, resources and a solid understanding of the potential pitfalls.

The first thing a company must do is to create a RoHS Compliancy Team, comprised of manufacturing engineers, purchasing, inventory, training and quality personnel. In many cases, reliability test engineers are also involved because the components and boards will change as will the solder; it may be necessary to verify the reliability of the lead-free, RoHS compliant assembly.

Procurement and Inventory Departments:

The purchasing personnel will have to work closely with board and component suppliers to ensure that lead-free compatible parts are available. Lead-free boards will also have to be sourced. In both cases, they will have to be lead-free and compliant to other requirements of the RoHS directive that is cadmium-free and halogen-free. It is recommended that all purchasing personnel familiarize themselves with these new requirements since they involve more than the elimination of lead, cadmium and halogens.

In many cases, the lead-free SMD components must be compliant to the J-STD-020 for moisture-sensitive levels. This standard will dictate the thermal profiles the components can withstand without damage. Many lead-free components are also following the guidelines set forth by the JESD97, as to the finish that will be available on the leads and also the type of interconnect used in BGAs.

To simplify the process, an Excel spreadsheet can be created by procurement and sent to each supplier. The supplier can indicate compliance to the RoHS, J-STD-020 and JESD97 for each component. The components may have new part numbers.

The process of searching out lead-free, RoHS components will be a demanding exercise. Boards will be easier to obtain. However, this process usually takes a company the longest in the transition process; it can take anywhere from three months to a year. For this reason, a company may choose to build one product at a time in lead-free format.

Components and boards that are not for lead-free assembly will have to be depleted and replaced with RoHS-compliant items.

Manufacturing and Engineering:

Process engineers will have to determine the lead-free alloy and flux systems to be used. Working with a solder supplier who has solid lead-free experience will save considerable time and money. Choosing the right alloy for the assembly and the right lead-free flux system will ensure reliability and also will help maintain production yields.

The equipment will have to be lead-free compatible. For example, the wave solder machine will require leach-resistant solder pots, impeller and ducting to avoid iron erosion with the higher tin-containing lead-free solders such as tin-silver-copper and tin-copper alloys. The reflow oven will have to be able to give higher peak temperatures in the range of 230°-245°C, but also be able to maintain production outputs at these thermal profiles. Soldering irons will require lead-free tips. Rework stations for BGA components will require narrower temperature control and the ability to sustain smaller Delta Ts; it will have to be investigated to see if it is lead-free compatible.

From an ease of implementation viewpoint, the easiest to the most difficult lead-free process to transition is as follows
:
• Lead-free Hand-soldering
• Lead-free SMT
• Lead-free Wave Soldering
• Lead-free Rework.

Lead-free may require the implementation of other process verification methods, such as X-ray, to examine lead-free joints for voids.

Documentation and Training
Lead-free solders offer different wetting behaviors and also less reflective cosmetics. Training will be required so that operators will be in a position to recognize good lead-free solder joints. At this time, there is no document available to use as a lead-free guide; however, the IPC will be issuing an addendum to the J-STD-610C in 2005.

Training of all personnel from purchasing to manufacturing and final assembly will prevent reliability issues and cross-contamination problems especially where dual systems, leaded and unleaded assembly, is being performed. It is also mandatory to review ISO documentation for compliance, updating or adding documentation to support the lead-free initiative.

The above is only a summary of some of the requirements needed to create a solid RoHS/Lead-free roadmap. The transition to lead-free is being achieved reliably around the world, but it takes proper planning and time. A successful transition can take six months to a year. The time to start is now if a company is to meet the July 1, 2006 deadline.

For more information on how to create a RoHS-Lead-free Roadmap for your company, please contact Peter Biocca at 972.390.1197 or pbiocca@kester.com.